21251639 ÷ 863 
Let's see how many times 863 fits into 21251639.

Moving on to step 1:
The number 863 fits into 2 0 times, leaving a remainder of 2.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Append the next digit (1) from the dividend to 2 and continue with: 21 / 863

Step 2:
If we divide 21 by 863, we get 0 and a remainder of 21.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 21 after subtracting 0 from 21.
Append the next digit (2) from the dividend to 21 and continue with: 212 / 863

Going ahead to step 3:
863 goes into 212 0 times with a remainder of 212.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 212 after subtracting 0 from 212.
Fetch the next digit (5) from the dividend, attach it to 212 and continue: 2125 / 863

Moving on to step 4:
The number 863 fits into 2125 2 times, leaving a remainder of 399.
Put 2 as the next digit of the answer. 
Result so far: 2.0
If we subtract 1726 from 2125, we get 399.
Take the next digit (1) from the dividend and append it to 399, then repeat: 3991 / 863

Moving on to step 5:
863 goes into 3991 4 times with a remainder of 539.
Put 4 as the next digit of the answer. 
Result so far: 24.0
If we take 3452 away from 3991, we end up with 539.
Include the next digit (6) from the dividend after 539, then repeat: 5396 / 863

Let's proceed to step 6:
The number 863 fits into 5396 6 times, leaving a remainder of 218.
The number 6 becomes the next digit in our result. 
Result so far: 246.0
If we subtract 5178 from 5396, we get 218.
Fetch the next digit (3) from the dividend, attach it to 218 and continue: 2183 / 863

Step 7:
2183 divided by 863 is 2 with a remainder of 457.
Use 2 as the next digit of our solution. 
Result so far: 2462.0
The remainder is 457 after subtracting 1726 from 2183.
Append the next digit (9) from the dividend to 457 and continue with: 4579 / 863

On to step 8:
If we divide 4579 by 863, we get 5 and a remainder of 264.
Put 5 as the next digit of the answer. 
Result so far: 24625.0
Subtracting 4315 from 4579 leaves us with 264.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2640, and continue the process.

Moving on to step 9:
When dividing 2640 by 863, we get 3 with a remainder of 51.
The next digit of our result is 3. 
Result so far: 24625.3
If we take 2589 away from 2640, we end up with 51.
Since there are no more digits in the dividend, we add a zero to the remainder making it 510, and continue the process.

Moving on to step 10:
If we divide 510 by 863, we get 0 and a remainder of 510.
Use 0 as the next digit of our solution. 
Result so far: 24625.3
If we take 0 away from 510, we end up with 510.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5100, and continue the process.

On to step 11:
If we divide 5100 by 863, we get 5 and a remainder of 785.
The number 5 becomes the next digit in our result. 
Result so far: 24625.305
The remainder is 785 after subtracting 4315 from 5100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7850, and continue the process.

Moving on to step 12:
863 goes into 7850 9 times with a remainder of 83.
The number 9 becomes the next digit in our result. 
Result so far: 24625.3059
The remainder is 83 after subtracting 7767 from 7850.
Since there are no more digits in the dividend, we add a zero to the remainder making it 830, and continue the process.

Step 13:
863 can be fit into 830 0 times, resulting in a remainder of 830.
Write down 0 as next digit of the result. 
Result so far: 24625.3059
Deduct 0 from 830 and we're left with 830.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8300, and continue the process.

Moving on to step 14:
863 can be fit into 8300 9 times, resulting in a remainder of 533.
Put 9 as the next digit of the answer. 
Result so far: 24625.305909
If we take 7767 away from 8300, we end up with 533.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5330, and continue the process.

Advancing to step 15:
When dividing 5330 by 863, we get 6 with a remainder of 152.
Record the quotient 6 as the next digit in the result. 
Result so far: 24625.3059096
If we take 5178 away from 5330, we end up with 152.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1520, and continue the process.

Step 16:
When dividing 1520 by 863, we get 1 with a remainder of 657.
Record the quotient 1 as the next digit in the result. 
Result so far: 24625.30590961
Deduct 863 from 1520 and we're left with 657.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6570, and continue the process.

The final outcome is 24625.30590961, with a leftover of 6.57e-07.